Countersinking tool



Aug. 26, 1952 M. M. MARTIN E'rAl.

COUNTERSINKING TOOL.

Filed Oct. 17, 1950 INVENTUM.

HUBERT M. BROWN 8 MARVIN M. MARTI/V,

A T TOM/EK Patented Aug. 26, `1952V ooUNTERs-INKING lTooL Marvin M. Martin, Bell, and Hubert M. Brown, Los Angeles, Calif.; said Brown assigner to said Martin Application October 17, 1950, Serial No. 190,544

` 6 claims. (c1. 77 73.5)`

Our invention relates to control mechanisms for regulating the depth of penetration of tools into work pieces.

While the principles involved are applicable to various types of cutting tools and the like, especially where accuracy and uniformity are desirable, the invention is particularly adapted for regulating the depth of penetration of drills or the depth of cut of countersinking tools. the purpose of disclosure and illustration the invention willbe described as applied toa countersinking tool.

A device of the type here under consideration includes some type of housing member that permits predetermined relative longitudinal movement of the tool and also includes a stop member in screw-threaded engagement with the housing member. The stop member abuts against work pieces for adjustably limiting penetration by the tool. Our invention meets certain pressing needs for improvement in the manner in which such a stop member is adjustably locked against rotation relative to the housing member.

One such need is to save time in changing from one depth adjustment to another. Ideally the operator should be able to snap the control mechanism from one depth adjustment to another insome simple manner and with accurate measurement of the extent of adjustment change. The present invention makes such a change in adjustment possible in practically one continuous hand movement by the operator. y

Another need is to avoid diculties caused by foreign particles lodging between co-acting engagement surfaces of such elements as shoulders, teeth, keys, notches and the like where such elements are used for setting the device at various depth adjustments.

Our invention shields such co-acting engagement surfaces by suitable surrounding walls and further provides for sliding Vengagement to make the co-acting surfaces self-cleaning.

The preferred form of the invention employs longitudinal or axial sliding engagement for adjustably locking the two cooperating parts against relative rotation. A special advantage of such an arrangement is that any foreign particles lodged in the locking mechanism merely limits the extent of the relative axial movement without affecting the accuracy of the rotary positioning of the parts'. f

To meet these and other needs for inventive improvement our invention provides a locking sleeve that slidingly surrounds both the housing member and the stop member, being keyed to For one of the members to move axially into sliding locking engagement with other member at selected positions of relative rotation between the two members. A suitable spring normally holds the locking sleeve in locking position but readily permits manual retraction to free the stop member for rotary adjustment. Merely releasing .the sleeve causes automatic locking at the new adjustment.

Other features and advantages of our invention will be apparent from the following detailed rdescription taken with the accompanying drawings.

In the drawings:

Figure 1 is a side elevation of the preferred form of the invention;

Figure 2 is a fragmentary view on a larger scale partly in section showing how the sleeve retracts to free the. rotary stop member;

Figure 3 is a view in longitudinal section on the same scale;

Figure 4 is a transverse sectional view taken on the line 4-4 in Figure 3; and

Figure 5 is an enlarged transverse sectional view taken on the line 5 5 in Figure 3.

The principal parts of the embodiment of the invention shown in the drawings include a rotary tool shaft I0 having a radial flange II, a housing or housing member generally designated l2 surrounding the shaft, a stop member generally designated I3 and a locking sleeve generally designated I4.

The shaft I0 which is adapted to be power driven in the usual manner holds a countersinking tool I 5 which may have a pilot or guide point I'I, a cutting portion I8 and a tapered shank I9. In the construction shown the tapered shank I9 seats with friction grip in a tapered socket 20 in the tool shaft I0 and may be released whenY desired by the thrust of a knock-out pin 2l.

The housing I2 may be made in two cylindrical parts, an upper part 22 having an end wall 23 and a lower part 24 of smaller diameter. These two parts of the housing I2 areV assembled together by screw-threads as shown and the lower part 24 has relatively fine peripheral threads 25 for adjustably holding the stop member I3; Mounted with a forced t inside the lower part 24 of the housing is a bushing 2B which forms a bearing for the shaft I B.

Inside the housing I2, a suitable helical spring 2'1 sleeves the shaft I0 and acts in compression between the shaft ange Iland the bushing 26 l to urge the shaft flange towards the end wall A23,

thus tending to retract the tool I5 into the housing as shown in Figure 3. It can be pointed out here that the defining edge of the opening in the wall 23 very closely circumscribes the shaft I0 and this prevents entry intov the housing of foreign particles.

The stop member I3 is of cylindrical configuration and has suitable side vapertures 2B for the discharge of cuttings and chips formed by the tool I as well asto permit observation of the tool I5. In eff-ect, the stop member I3 is an adjustable extension of the housing I2 by means cf which the over-all length of the device may be varied for controlling the depth of penetration of the tool I5.

As best shown in Figures 3 and 4, the locking sleeve I4 may be keyed to the housing I2 by a suitable dimple or offset 29 that sliding engages a key-way 30 in the housing l2. Thus the locking sleeve I4 is held against relative rotation but is free to slide on the housing towards and away from locking engagement with the stop member I3. For continuously urging the locking sleeve I4 into such ,engagement a suitable helical spring 3l is compressed between an inner radial flange 32 rof the locking sleeve and an annular shoulder 33 formed by the upper part 22 of the housing I2. Preferably the periphery of the locking sleeve is knurled as shown in Figure 1 to facilitate manual retraction against the resistance of spring 3l.

While the locking sleeve I4 and the stop member I3 may be adapted in any suitable manner for mutual locking engagement to prevent rotation of the stop member, preferably the two parts telescope into engagement with the engaging surfaces sliding past each other longitudinally of the device. For this purpose the stop member I3 is formed with a radial locking portion 35 of non-circular configuration in plan and an adjacent radial stop portion 36 which may be circular in plan. The previously mentioned inner radial flange 32 of the locking sleeve I4 is of non-circular configuration in plan to slidingly interlock with portion and move into abutment with stop shoulder 36.

While various non-circular interlocking configurations may be used I prefer the interlocking relationship best shown in Figure 5. Note that the plan configuration of the locking portion 35 is that of a hexagOIlLl nut with six pointed locking shoulders 31 while the edge face of the coacting flange 32 is formed with a plurality of equally spaced teeth or serrations 38 for interlockingly engaging the shoulders 31 selectively at a number o f different positions of relative rotation.

The arrangement may be described as one in which the locking sleeve is continuously keyed to the housing I2 for axial movement relative thereto, but is adapted for retractibly and selectively keying with the stop member I3 at a number of different positions of relative rotation.

The lower end of the locking sleeve I4 may be provided with agraduated scale 39 to be read with reference to an index mark 40 on the stop member I3, each graduation corresponding to one of the multiple notches or key ways 4I formed by the serrations 38 of the locking fiange 32. Preferably the pitch of the fine threads 25 and the number of the key ways 4I are such that one graduation represents one thousandth of an inch adjustment in the depth cf penetration of the tool I5.

To change the adjustment of the device, the operator merely retracts the locking sleeve I4 with a quick motion by one hand, twirls the stop member I3 to a new position with the other hand and then releases the locking sleeve to re-lock the stop member. The tool is now ready for use.

It should be noted that the range of reciprocation of the tool I5 is limited at one end by the abutment of the flange II against the inner side of the end wall 23 of the housing member I2. As the'tool is first brought into engagement with the work piece and the pilot pin I1 passed downwardly into the opening, which is to be countersunk, the flange II will move out of engagement with the end wall 23 before the shaft I0 is rotatably driven. There is thus no frictional engagement between the flange II and the end wall 23 during the time that the shaft is driven.

Movement of shaft III in the opposite direction is limited by engagement of a thrust bearing 42 fixed to the shaft IU, referring to Figure 3, with the upper end face of the lower housing part 24. It should be noted here that the spring 21 in this relative position of' the shaft Ill will be compressed within the anular chamber 43 formed about the shaft IIl by the bushing 26 and the lower housing part 24. The thrust bearing 42 effectively prevents any temperature risc which might otherwise be caused by frictional engagement .between the now rotating flange I I and the end face of the lower housing part 24.

It is to 'be noted that the sleeve spring 3| is completely enclosed at all times and that the interlocking surfaces are shielded by the telescoping of the locking sleeve I4 over the stop member I3. Any small foreign particle lodged between the locking sleeve I4 and the' stop member I3 will merely limit the relative sliding movement `without preventing the desired interlocking relationship. Since such particles tend to be dislodged by the sliding movement, the interlocking surfaces are in effect self cleaning.

To further prevent entry of foreign particles into the device, the stop member I3 is formed on its inner wall with an inwardly directed annular flange 44, the inner edge face of which closely circumscribes the tool I5. It will thus be seen that the flange 44 forms a guard or shield effective t0 prevent entry of chips and metal cuttings into the upper portion of the stop member I3, which might otherwise foul the threads thereof. As metal cuttings or chips might become ernbedded in the lower face of the stop memberv as the same is repeatedly pressed into contact with work pieces, it is now preferred to deposit on the lower end of the stop member a hard chrome layer. This is preferredly done by an electroplating process.

Although the now preferred embodiment of the present invention has been shown and described herein, it is to be understood that the invention is not to be limited thereto, for it is susceptible to changes in form and detail within the scope of the appended claims.

We claim:

1. A device of the character described for adjustably limiting the downward thrust of a tool relative to a work piece, comprising: a housing member slidingly engaging the tool and limiting the downward thrust. of the tool relative thereto; a stop member for contact with a work piece to fix the spacing of said housingr member relative to the Work piece, said stop member being in screw-threaded engagement with the housing member for adjustment of said spacing by relative rotation between the two members; a first circular series of locking shoulders on said stop' 2,eos,1 14

member; a locking sleeve extending above said stop member and keyed to said housing for axial movement relative to the stop member; a second circular series of locking shoulders on the interior of said locking sleeve for retractable downward movement with the locking sleeve into interlocking engagement with said iirst series of shoulders,

said second series of shoulders being spaced up-` ward from the lower end of the sleeve whereby said lower end normally encloses both series of shoulders when the two series are interlocked thereby to discourage the entrance of foreign material into the region of the interlocked shoulders; and yielding means acting between said sleeve and housing to urge the sleeve downward into locking position.

2. A device as set forth in claim 1 in which said lower end of the sleeve extends below said second series of shoulders sufciently to enclose said first series of shoulders when the sleeve is retracted to disengage the two series of shoulders.

3. A device as set forth in claim 1 in which said stop member has an external wall below said rst series of shoulders telescopically tting into said lower end of the locking sleeve.

4. A device as set forth in claim 3 in which said lower end of the sleeve extends below said second series of shoulders suciently to surround said external wall of the stop member when the locking sleeve is retracted to disengage the two series of shoulders.

5. A device of the character described for adjustably limiting the downward thrust of a tool relative to a work piece, comprising: a housing member slidingly engaging the tool and limiting the downward thrust of the tool relative thereto; a stop member for contact with a work piece to extending downward to the region of an ,outer circumferential surface of said stop member; a second series of locking shoulders on the interior of said locking sleeve for retractable downward movement with the lockingY sleeve into engagement with said rst series of shoulders, said second series of shoulders being spaced upward from the lower end of the sleeve; yielding means to urge said sleeve into locking position; and index means on said two outer surfaces to indicate the rotary position of said stop member relative to said housing member.

6. A device as set forth in claim 5 in which said index means includes a graduated circumferential scale on said outer cylindrical surface.

MARVIN M. MARTIN. HUBERT M. BROWN.

REFERENCES CITED The following references are of record in the file of this patent: n

1 UNITED STATES PATENTS Number Name Date 2,294,303 Jagow Aug. 25, 1942 2,402,252 Trautmann June 18, 1946 2,409,377 Miller Oct. 15, 1946 

